In the art of the drawing of stainless steel and nickel alloy wire and rods, older methods of providing a lubricant or lubricant carrier coating such as a lead coating, an oxalate coating or lime coating have been largely superseded by salt coatings. These salt coatings are formed by immersion is concentrated solutions containing sodium chloride, borax and sodium metasilicate.
Such compounds have enabled high speed multi-hole drawing to be carried out but suffer from the disadvantage that residual chloride on the wire after drawing can give rise to pitting corrosion. Attempts have been made to overcome this problem by replacing the sodium chloride with alkali metal sulphates but these have given rise to further problems in that the coatings produced are hygroscopic and pick up water at such a rate as to seriously impair drawing performance.